This application claims priority from United Kingdom Application No.: 97117881 filed Jun. 6, 1997 in the name of Northern Telecom Limited.
This invention relates, generally, to a communication system architecture and operating protocol therefor, and is particularly, but not exclusively, applicable to an interface arrangement that integrates a local area network (LAN), typically operating in a wide-band context, with a broadband virtual circuit-switched system, such as envisaged and implemented in Asynchronous Transmission Mode (ATM) networks.
Telephony systems have evolved from simplistic hard-wired interconnected networks to broadband, high capacity systems that support multimedia, multi-mode communication devices on local area networks (LANS) and packet-switched communication systems. Indeed, instead of having to rely entirely on dedicated land-line infrastructure, present day technologies now occupy virtual channel environments in both the radio frequency and land-line domains.
The designers of today""s narrowband communication systems, which typically employ pulse code modulation at a data rate of 64 kilo-bits per second (kbps), are presently considering the adaptation and development of these narrowband communication systems to support a migration to a multimedia environment having data rates of two (2) Mega-bits per second (Mbps) and beyond. As will be understood, the requirement for migration arises as a direct consequence of the vast costs involved in deploying global communication systems, with ATM being touted as providing a low cost and simple package that is capable of supporting migration from narrowband (or wide-band) to broadband applications (principally in the intervening period before the full deployment of a free-standing Universal Mobile Telecommunication System (UMTS), for example).
It has also been necessary for designers to consider and anticipate the extensive and elaborate requirements for future control signalling and call management techniques. In this respect, new signalling schemes, such as AAL-2 negotiation procedures, have been developed to provide robust, high bandwidth communications at high data rates, while designers have also been keen to define system architectures in terms of xe2x80x9cstacksxe2x80x9d that comprise discrete layers of infrastructure or signalling protocols that each add functionality, capacity or control over a preceding layer in the stack.
The problems faced by system designers are further exacerbated by the fact that, to date, the various different forms of communication system, e.g. ATM, LANs and cellular radiotelephone schemes, operate distinct signalling and transport protocols that are incompatible on a network-to-network basis.
GB-A-2311690 describes the merging of two networks in which a telephone subsystem is connected to a packet-switched broadband backbone and in which telephony is added to the backbone without interfering with packetised data. GB-A-2309362 is a mechanism for interconnecting broadband and narrowband networks and is generally related to the present field of the present invention.
WO 96/06492 is an arrangement for supplying local network emulation service over a public connectionless ATM network. More specifically, a server acts as an address resolver and as a relay for routing traffic. SynOptics U.S. Pat. No. 5,420,858 describes the segmentation and re-assembly of information between non-ATM messages and ATM cells.
U.S. Pat. No. 5528590 describes the transfer of data between an ATM-UNI interface and an ATM-LAN interface in a manner such that the ATM-UNI interface recognises frames and assembles and ATM cells into these frames. More particularly, the system can determine whether or not there is enough capacity on the LAN interface for the frame, and only if there is enough capacity is the frame transferred via a ATM switch to the ATM-LAN interface and then onwards to the LAN.
It is therefore clearly desirable to design and produce a communication system architecture that supports varying types of present-day communication network, with the communication system architecture at least possessing an interface that has the capability of handling broadband signalling and transport schemes and which also contemplates the interconnection of LAN or WAN architectures to such broadband networks.
In a first aspect of the present invention there is provided a method of connecting a first network to a second network via an intermediate network, the first network and second network using a set of control messages to control media paths between the first network and the second network, the method comprising the steps of: establishing a control channel across the intermediate network to carry the set of control messages; intercepting the set of control messages in the intermediate network and determining a requirement for media paths in response thereto; in response to the determination, setting up media paths in the intermediate network to connect paths to carry media traffic between the first network and the second network.
In another aspect of the present invention there is provided a method of connecting communication traffic comprised of a plurality traffic components across a broadband network from a local area network, the method comprising the steps of: in the local area network, generating control messages for controlling the traffic components and applying these control messages to an interface of the broadband network; establishing a communication path within the broadband network to carry at least one of the plurality of traffic components; and in the broadband network, using the control messages to control transfer of the plurality of traffic components over the communication path.
In another aspect of the present invention there is provided a method of interconnecting communication traffic across a broadband network from a local area network (LAN), the broadband network having a transfer protocol that supports mini-channels in a virtual circuit-switched environment, the LAN (10) providing the communication traffic as LAN streams to an interface of the broadband network, the method comprising the step of mapping the LAN streams to the mini-channels.
In a preferred embodiment, the LAN streams include audio, video, data and control streams, and the method further comprising the step of interpreting the control streams to set-up mini-channels used to carry at least one of an audio, video and a data communication.
In yet another aspect of the present invention there is provided a connection supervisor for orchestrating the communication of traffic components between first and second networks via an intermediate network, the connection supervisor responsive to control messages communicated between the first and second networks, the connection supervisor including: means for setting-up a communication path for carrying the control messages across the intermediate network; means for determining types of control message sent across the communication path; and means for establishing media paths dependent upon types of control message sent across the communication path, the media paths arranged to transfer the traffic components across the intermediate network.
In still yet another aspect of the present invention there is provided a communication node having a gateway that provides an interfaces to a first end-point in a network, the first end-point arranged to initiate a call through the communication node by sending to the gateway a called party number of a second end-point coupled to an exchange and wherein control messages are communicated between the first end-point and the second end-point, the communication node further comprising: a call handler coupled to the gateway and responsive to the called party number, the call handler arranged to select a route to the exchange; and a connection supervisor, coupled to the call handler and operationally responsive thereto, the connection supervisor having: i) means to set-up a control channel that supports transfer of the control messages between the gateway and the exchange in response to the call handler receiving the called party number; ii) means for determining types of control message sent across the control channel; and iii) means for establishing media paths between the gateway and the exchange (118) dependent upon types of control message sent across the control channel, the media paths arranged to transfer traffic components across the communication node.
In a preferred embodiment, the communication node is a broadband network and the control channel and the media paths are virtual channels.
Beneficially, the preferred embodiments of the present invention generally provide an ability of interconnecting a first LAN-compatible system (such as a WAN) through a seamless public or private broadband network (supporting narrowband or broadband telephony) to another LAN-compatible system.